Pneumatic-despatch-tube apparatus.



M. L. EMERSON.

PNEUMATIC DESPATGH TUBE APPARATUS.

APPLICATION FILED SEPT. 16, 1911.

1,109,827, Patented Sept. 8, 1914'.

THE NORRIS PETERS CO., PHO'lO-IJI'I'IO0 WASHINGTUN. D, C.

UNITED STATES PATENT OFFICE.

MERTON L. EMERSON, OF BRAINTREE, MASSACHUSETTS, ASSIG-NOB. TO AMERICAN PNEUMATIC SERVICE COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION OF DELAWARE.

PNEUMATIC-DESPATCH-TUBE APPARATUS.

Specification of Letters Patent.

Patented Sept. 8, 1914.

Application filed September 16, 1911. Serial No. 649,685.

pneumatic despatch tube apparatus and especially to mechanism for controlling the power machinery which compresses the. air above that of atmosphere for driving carriers through the pneumatic tubes.

The principal object of my invention is to obtain the highest economy in the operation of compressed air systems by reducing to a minimum the amount of power requlred to operate, that is, the power is used only at its highest eificiency, thus savlng the Waste consequent in a plant always running at highest speed.

In the accompanying drawings which illustrate a construction embodying my invention, Figure 1, is a diagrammatic view illustrating my device connected to pneumatic tubes through which carriers are trans mitted by compressed air. Fig. 2 is a front view of the lock and timing device controlling the power machinery and illustrating the parts in position when the power is running at low speed. Fig. 3 is a similar view to Fig. 2 illustrating the position of the parts when the power machinery is starting in operation at high speed to drive carriers through the tube line.

Like letters of reference referto like parts throughout the several views. 1 In the form of apparatus shown in the drawings, A represents a senderlocate'd at each end of the line which consists ofva loop line of tubing A extending between two stations; A is an electric switch at eachsender which may be operated by theinsertion of a carrier into the sender for transmission or by hand if desired. The electric motor B is adapted to operate the compressor C which is provided with a check 1 valve C at the intake which allows air to flow in but prevents its escape. The pipe G leads from thecompressor C tothe line has a check valve C which allows pressure to accumulate in the tank D but prevents 1ts return to the compressor. On the switch board E is mounted the timing mechanism F and the controlling motor switch G.

v G represents the main feed wires running to the motor B.

H is an auxiliary electric circuit which controls the running of the motor B at high or reduced speed and H? is an auxiliary electric circuit connected with the field of the motor B, and the object of this circuit s to reduce the speed of the motor when no carriers are being transmitted by cutting out more or less resistance and thereby reducing the speed of the motor; and when carriersare being despatched, more or less resistance is" cut in, thereby causing the motor to run at a higher speed than when no carriers are in transit.

The carrier to be despatched is placed in sender A and momentarily closes the switch A as it passes over it, thereby closing the auxiliary circuit H and causing the'valve F in the solenoid F to be drawn upwardly. This movement opens the valve F3 and permits the air supply in the storage tankD to pass through pipe F to thebottom of the cylinder F The compressed air then forces the floating piston Fto the top of cylinder F as the space above the piston F is open to the atmosphere through the vent F Below the piston F is a valve casing F containing the piston valve F stem F and spring F. This piston valve F controls the .flowpfcompressed air vfrom the pipe F to the pipe G. Stem F eXtendS into the bottom of the cylinder F as shown in such away that when the floating piston F is at its lowest position, the piston valve F is pushed down by stem F against the spring F 7 thereby closingcommunication between the pipe F andpipe G so that air cannot pass from pipe F into pipe G. l/Vhen piston F is raised by opening the valve F as previously described the spring F raises the piston valve F and permits valve casing F to pipe G and thence to the bottom of the cylinder Gr of the controlling switch G. ,The compressed air then forces up piston Gr to the top of compressed air to pass from pipe F through cylinder G3; and I also the piston rod G pivotally connected to the switch G at G of providing a constantly driven or running and this movement operates the switch G and moves it to the position shown in Fig. 3 which will cut in all resistance and start the motor B at full speed. As the carrier passes into the transit tube A the switch A is opened and the auxiliary electric circuit H is broken and the breaking of this circuit causes the valve F to close by gravity so that the piston F" drops by gravity as the space below the piston F is open to the atmosphere through the controlling valve F The drop of the piston F is regulated in speed by off from the bottom of the cylinder G The compressed air in pipe G and in the bottom of. cylinder G is vented to the atmosphere through port F in the top of the valve casing F and the pistonG therefore drops by gravityimmediately, thus moving the arm G to the position shown in Fig. 2, in which position the resistance is cut out through circuit H and the motor is slowed down. From the foregoing, it is obvious that a great saving of power is obtained in operating a pneumatic tube system with my device, as the power machinery for compressing and driving the air is used only at high speed when carriers are in transit and is automatically slowed down when the last carrier inserted in the .line has discharged.

The dropping of the piston F in the timing mechanism F is controlled by the valve F? as explained. It is clear that the switch G would remain closed and the power machinery continued in operation at full speed until the piston F returned by gravity to its normal position. Inasmuch as the descent in this piston 13 is controlled by valve F it follows that the interval of time that the power machinery is running at high speed is also controlled by this valve F. As the timing mechanism F is reset by the introduction of each carrier into one of the senders A, it follows that the power sire to point out particularly the advantage motor and blower in combination with timing means of the character in question, since I am aware that attempts have been made to provide somewhat analogous timing means in combination with a motor and blower which are normally brought to rest after the transmission of a carrier. In the first place, if the motor be allowed to stop, current is wastefully consumed in starting it again, and it is one of the objects of the present invention to largely obviate such waste of energy; a considerable economy being efiected in many instances by thus allowing the motor to drive the blower at a determined minimum speed and to speed up the blower a determined amount for a predetermined time for carrier transmission purposes. There is further an inter-relation between the constantly running but variably driven motor and the timing mech anism herein described, since the time period is affected. Any construction which tends to reduce this period not only favors the economy of the system as a whole, but permits of theuse of less bulky or less finely adjusted timing mechanism.

The inter-action between the timing mechanism and theconstantly driven motor results from the following state of facts: Let us assume that the motor and blower are at rest, and that a carrier is to be despatched from the right hand station shown in Fig. 1. Obviously the air in the pipe C and A is quiescent and is furthermore at substantially atmospheric pressure. Vhen the blower starts to deliver air to the pipe or conduit C air in the so operated system will be successively compressed along the length of said pipe and thereafter along that of pipe A until suflicient compression of the air immediately back of the carrier to be transmitted has been attained to start said carrier. This consumes time and results in the time period being of longer duration under such conditions than is the case where the motor and blower are continuously driven and the speed thereof merely increased a determined amount for transmitting carriers; since, in this case, the air in pipe C and A is already subject to some compression and is furthermore under way or in movement, so that the inertia, of what we may conveniently term the column of air, which has to be overcome when the blower is continuously operated is not as great as when the air is started from rest. There is a true co-action, therefore, between the elements of the present construction, hereinafter more particularly pointed out-in the'claims, which results in certain economies of operationwhich in the case of long bodying the same, What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a pneumatic despatch tube apparatus, a station, a tube for the transmission of carriers from said station, a continuously operated motor set to operate within a certain range of speed, a pump continuously driven by said motor, mechanism, controlled from said station, for increasing the speed of said pump to maximum for the transmission of a carrier through said tube, said mechanism having means to return said pump to its minimum speed, and timing means for controlling said last mentioned means.

2. In a pneumatic despatch tube apparatus, a station, a tube for the transmission of carriers from said station, a continuously mg said pump, said pump being normally driven at a determined minimum speed,

means controlled from said station for increasing the speed of said pump to transmit a carrier, inserted at said station, through said tube, and timing means for normally limiting the duration of said departure in speed from said minimum, to a substantially determined interval of time.

i In testimony whereof, I have signed my name to this specification in the presence of two subscribing Witnesses, this 12th day of September A. D. 1911.

MERTON L. EMERSON. lVitnesses ESTHER A. GOUGH, M. G. MACMILLAN.

Copies of this patent may be obtained forfive cents each, by addressing the Commissioner of Eatents, Washington, D. C. 

